1. Field of the Invention
The present invention relates generally to liquid vaporizers for dispensing volatile liquid materials such as fragrance oils and solutions, deodorants, insecticides and the like, and, more particularly, the present invention relates to a method and apparatus for controlling the rate of liquid evaporation.
2. Background of the Invention
Electrical liquid vaporizers (often referred to as xe2x80x9cliquid electricsxe2x80x9d) are generally well known in the prior art. Typically, such electric liquid vaporizers comprise a housing unit configured to receive a bottle or liquid container portion. The bottle portion contains a wick or wicking system through which the volatile liquids can be migrated to a portion of the wick that is exposed to the air. The exposed portion of the wick is generally heated by a heating element disposed within the housing unit and proximate to the wick in order to suitably facilitate the vaporization of the volatile liquid to be dispensed therefrom.
Various methods for attempting to control the rate of evaporation of volatile liquids have been designed and marketed for electric liquid vaporizers. For example, some electric vaporizers have an annular collimation mechanism to mechanically control the orifice size, while others have means to mechanically control the position of the wick relative to the heating element. However, such mechanical controlling devices have generally been found to be somewhat ineffective in controlling the rate of liquid evaporation. Alternatively, other electric liquid vaporizers use an electrical switch to turn the electrical power on and off; however, the electrical ON/OFF switch does not provide different evaporation rates for variable delivery of fragrance intensity. Polarized plugs are desirable for liquid vaporizers employing a wick that must be oriented vertically or substantially upright. Furthermore, for safety concerns, polarized plugs are desirable if an electrical ON/OFF switch is part of the unit in that inadvertent polarity reversal might permit the device to operate while in the xe2x80x9cOFFxe2x80x9d setting. The need for a polarized plug also tends to complicate the assembly process. In some applications, the polarized plug may not be an optimum choice for plug-in air fresheners because of a lack of convenience to users. For example, there are often outlets that are not compatible with the vaporizer having a polarized plug or where the polarity of the outlet has been unknowingly reversed (e.g., those in older residential homes or those with polarity misoriented).
In attempting to control the rate of evaporation of volatile liquids from an electric liquid vaporizer, it is also be desirable to have means for compensating for voltage and/or current fluctuations in order to substantially maintain (once set) a temperature suitably adapted for a user-selected level of fragrance delivery.
Thus, the prior art, taken either alone or in combination with existing delivery systems, fails to teach approaches that permit effective control of the rate of evaporation and the level of fragrance intensity.
The present invention suitably provides a method and apparatus for controlling the temperature of a liquid vaporizer heating element, and thereby the rate of evaporation and level of fragrance delivery from the same. In accordance with one exemplary embodiment of the present invention, the device may include a switch that suitably allows the temperature of various types of heating elements to be controlled for different levels of fragrance output. For example, an exemplary embodiment may include a two-pronged plug adaptable to typical outlets that might be found in residential homes or businesses. In accordance with another exemplary embodiment of the present invention, the electrical switch generally provides varying resistance values to the electric circuitry of the vaporizer such that, by changing the switch setting, the operating temperature of the wick is controlled and thus the rate of fragrance evaporation from the vaporizer.